I bought two battery packs from ping - one was 36v 40Ah and one was 48v 40Ah. Because the are quite large, each pack came in two halves. At one end of each is a single thick wire with an Anderson connector, so that the two can be connected in series. At the other end of each pack, there is a thick power output wire (red and black respectively) and a thinner wires (again red and black respectively) which must be for charging. A voltmeter gave identical readings on the power and charging wires.The BMS is attached to the negative half of the pack and there is a group of thin wires connecting to the other half of the pack via a multipin connector (these are presumably monitoring each cell voltage).

I connected up the 36v pack to its charger (supplied by ping) and it charged up fine.

But when I connected the 48v pack in the same way, something very strange happened. Before charge the two halves were reading 19v and 22v respectively, and the overall voltage was 41v (which must mean that they were properly connected in series). While on charge the overall voltage reached the proper cut-off limit of 60v. But after disconnecting the charger the overall voltage was only 1.2v. On closer testing one half was reading 28.2v but the other half was reading MINUS 27.0v. ie this half has reversed its polarity.

I can't see that I have done anything wrong, because I carefully tested all the polarities and voltages while connecting the pack together, and connecting the charger. So has Ping wired up one half of the pack or the BMS wrongly?

An email to ping has produced an automated response that he is on holiday for the next 2 weeks (Chinese New Year or something) so any advice will be welcome.

(Incidentally, the BMS has a series of red leds - presumably one for each cell. If the light is showing, does that mean that the cell is properly charged, or does it indicate a fault?)

Jonathan Jewkes
Daily EV user for 10years - an enthusiast and also a realist

jonathan jewkes wrote:(Incidentally, the BMS has a series of red leds - presumably one for each cell. If the light is showing, does that mean that the cell is properly charged, or does it indicate a fault?)

.....the lights light up as each cell reaches their fully charged status, once all the LED's are lit, like in the picture then the pack is ready to use ( although in the picture I am awaiting for the last LED on the left to come on), there is also a red/green LED on the charger and this can turn green before all the LED's are alight on the BMS, you need to leave the charger connected until the LED's on the BMS are all on regardless of the charger LED.